The objectives of this project are to continue two randomized controlled intervention trials currently underway in Linxian, a county in north central China with one of the world's highest rates of esophageal cancer. This involves the monitoring of mortality and cancer incidence and maintenance of stored biologic specimens among 3,400 persons with esophageal dysplasia and 30,000 in the general population of this high- risk area who were supplied vitamin/mineral pills during 1985-91. All deaths and cancer occurrences--among the study populations will be recorded so that mortality and cancer incidence rates between-those receiving active pills vs. placebo can be contrasted to test the effectiveness of the nutrient supplementation in reducing cancer risk.